England fans have been warned they could be targeted by Russian spies at the World Cup

He warned strangers who struck up conversations in bars and other public places could be undercover agents, trying to establish friendships that could be exploited.

He told The Times: “People are giving out a lot of information when they travel to Russia: names, addresses, social security numbers. That data is installed in systems of the Russian special services.”

Mr Marran has also advised those attending the World Cup in June and July to keep phones, laptops and other electronic devices with them at all times or not to bring them at all.

He added: “It doesn’t mean every fan is a target but there will be high-level officials visiting Russia, who might be possible targets."

An England fan holds up a flag prior to the International friendly match between England and Germany at Wembley Stadium in November

Of particular interest to Russia’s spy agencies are British and other western businessmen and women, government workers, military personnel, financiers and journalists - anyone who potentially has access to privileged information about their respective country.

Mr Marran said: “They are going to be looking at who are coming, where they are staying, what they are doing, what are the possibilities, weaknesses. We are trying to raise awareness that this is the risk.

“It doesn’t mean that you shouldn’t go to Russia. Russia is a great country. But just to make people more aware of what might be happening around them when they are happily having a pint in Moscow or someplace else.”

The Times reported that it is aware of a British journalist who was targeted by a female Russian spy at the bar of the hotel he was staying at on a working trip to Moscow in the 1990s.

Next morning the journalist’s notepad had disappeared and he had also contracted some form of illness — not a normal sexually transmitted disease — that left him unwell for several months, according to The Times.

Mr Marran appeared less concerned about the possibility of hooligans infiltrated by members of the Russian special forces clashing with fans as happened at the European Championships in 2016.

He said: “The World Cup is a huge PR project for (President) Putin. That probably means we will not see any major fights between hooligans on the streets in Russia.

“Go to Russia. Have fun, but be aware.”

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